Apparatus for forming a closure in a well bore



Jan. 31, 1961 H. M. GREENE 2,969,839

APPARATUS FOR FORMING A CLOSURE IN A WELL BORE INVENTOR. M flu flrmpzlgg2 Sheets-Sheet 1 ES/(EZL M. G'EEsA/E,

Filed May 11', 1957 Jan. 31, 1961 H. M. GREENE APPARATUS FOR FORMING ACLOSURE IN A WELL BORE Filed May 17, 1957 2 Sheets-Sheet 2 MS/(ELL Mgees/ME;

INVENTOR. Z4 ,lrmeugg.

2,969,839 Patented Jan. 31, 1961 APPARATUS FOR FORMING A CLOSURE IN AWELL BORE Haskell M. Greene, 8815 S. Highland Ave., Whittier, Calif.

Filed May 17, 1957, Ser. No. 659,945

4 Claims. (Cl. 166-63) This invention relates to improved apparatus forforming a bridge plug or closure in a well, to seal off an upper portionof the well from a lower portion thereof. The present application is acontinuation-in-part of my copending application Serial No.503,623,'filed April 25, 1955, on Application of Localized Gas Pressurein a Well, now abandoned. In certain respects, the apparatus disclosedin the present application may be considered as an improvement on theapparatus of my Pat ents Number 2,696,258, issued December 7, 1954, onOil Well Cementing Packer, and Number 2,696,259, issued December 7,1954, on Apparatus for Firing Propellent Charges in Wells.

The general object of the invention is to provide an improved type ofdevice which is capable of being lowered into a well, and which on asingle lowering can function to position a plug in fixed position in thewell, and also to deposit a body of cementitious material (preferablyPortland cement) on the plug, to harden while resting on the plug andthus form a permanent closure across the well bore. In the apparatusembodying the invention, the positioning of the plug and cement in thewell bore is eifected very rapidly, once the device is actuated afterbeing lowered into the well. Especially contemplated is an arrangementWhich is so designed as to maximize the rate at which the cement willset in the well, so that it will set before the well fluid has time toforce itself into the body of cement and thus adversely affect theeflfectiveness of the ultimate closure.

structurally, a device embodying the invention includes a hollow bodyadapted to be lowered into a well and carrying a bore closing plug, anda body of cementitious material above the plug, with the plug and cementbelng adapted for ejection downwardly from the body after lowering intothe well. For thus ejecting the plug and cement, I employ a charge ofgas producing propellant material which acts when fired to producepressurized gases above the cement in a quantity acting to force thecement and plug downwardly and from the body to their active boreplugging positions. Such ejection of the plug results in its actuationto a locking condition in which it is securely held in fixed position inthe well, to thereafter efiectively support the cement in the well.

As previously mentioned, a very important object of the invention is toprovide for rapid setting of the cement in the well, toprevent itscontamination before it can be set. For assuming this result, thepropellant charge proves especially helpful, since the high temperaturesdeveloped by burning of the propellant greatly accelerate the setting ofthe cement. Also, the pressure of the gases has a similar effect inaccelerating the setting action. This rapid setting of the cement,immediately following the ejection of the plug and cement into the well,causes the cement to become effective as a positive closure in a minimumperiod of time after the plug is placed in use. Consequently, the plugitself need not be designed to serve as a closure for any appreciableperiod of time.

Certain particular features of the invention have to do with theconstruction of a preferred type of plug. Specifically, this plugincludes gripping fingers for securing the plug in fixed position in thewell, and a radially expansible seal cup structure for assuringeffective closure of the well. Desirably, the seal cup structureincludes a flexible cup of rubber or other-deformable or elastomericmaterial, and a plurality of backing elements positioned beneath andsupporting the rubber. The backing elements may consist of a number ofthin sheet metal petals which overlap and form together a flaringradially expansible cup arrangement.

The above and other features and objects of the present invention willbe better understood from the following detailed description of thetypical embodiment illustrated in the accompanying drawings in which:

Fig. 1 is a vertical sectional view of a well tool constructed inaccordance with the invention;

Fig. 2 is a view corresponding to Fig. 1, but showing the tool after ithas been fired and the cement and plug have been forced from it to forma closure in the well;

Fig. 3 is an enlarged vertical section through the lower portion of theFig. 1 apparatus;

Fig. 4 is a transverse or horizontal section taken on line 4-4 of Fig.3;

Fig. 5 is a fragmentary perspective view of the upper portion of theplug in Fig. 3;

Fig. 6 is a fragmentary perspective view of the seal cup structure ofFig. 3;

Fig. 7 is a horizontal section taken on line 7-7 of Fig. 3;

Fig. 8 is a fragmentary view of a variational form of the apparatuswhich is the same as that shown in Fig. 1 except as to the particulartype of bore closing plug which is employed;

Fig. 9 is a transverse section taken on line 99 of Fig. 8;

Fig. 10 is a fragmentary vertical section through another from of theinvention; and

Fig. 11 is a fragmentary view of a final form of the invention.

Referring first to Figs. 1 through 7, the tool 10 there shown is adaptedto be loweerd into a well at the lower end of a flexible cable or line11, and functions when actuated to form a closure across the well boreclosing off an upper portion of the well from its lower portion. In thefigures, the well 12 has been represented as containing the usualtubular casing or liner 13, which may in some instances containperforations 14 through which the interior of the casing communicateswith the surrounding earth formation. When the casing or liner 13contains such perforations, it may be desirable to force some of thecement through those perforations and into a space 15 about the casing.In other instances, where the casing 13 is entirely imperforate, it maybe desired merely to form a cement wall or plug extending across butentirely within the casing.

The preferred form of tool 10 comprises essentially a tubular verticalextending body including four threadedly interconnected sections 16, 17,18 and 19, and containing a body of cementitious material 20, a gas gun21 carried by the upper end of the tool body and acting to direct thegases generated by a propellant charge 22 downwardly through the bodyand against the cementitious material, and tubular packer sleeve 23adapted to be radially expanded against the wall of the well (casing 13)to form a seal preventing upward dissipation of the actuating gases andtheir force. The cementitous material 20 is preferably Portland cement,which may contain an agent tending to speed its setting, and thismaterial will therefore be hereinafter referred to merely as cement. Inthe lower portion 16 of the tubular body, there is provided a plug 24which is ejected downwardly by the force of the generated gases to theFig. 2 position in which the plug serves to close off the bore at alocation spaced beneath the lower end of the tool body. The gas forcealso acts to force the cement 20 downa sil tram the ear and a e all tterm the ,desired cement closure above the plug 24.

The lower tubular portion 16 of the tool body may have its lower endclosed by a downwardly tapering nose member 25 which is attached to thebody in a manner permitting the nose member to be very easily blowndownwardly from the body upon ignition or" the propellant or gasgenerating charge 22. For this purpose, body section 16 may have several(typically four) evenly circularly spaced inwardly bent portions 26 (see:Fig. 7), which frictionally engage the upper externally cylindricalportion 27 of nose member 25 sufficiently tightly to friction ally holdthe nose member in the Fig. 1 active position of attachment to bodysection 16. This frictional engagement, however, is sutficiently lightto ,allow the nose member to be very easily displaced downwardly fromthe tool body by downward movement of plug 24 when propellant charge 22is fired.

The portion 17 of the tool body above its lowermost portion 16 containsthe body of cement 20, to the upper surface of which the gas pressureproduced by propellant charge 22 is communicated. The cement containingportion 17 of the tool body may of course be considerably longer thanwould appear from Figs. 1 and 2, in which views this portion of the bodyis broken away to allow for representation of the entire length of thetool in a single figure.

The cement 20 is supported in body section 17 by means of a horizontalor transverse bottom wall 28 which extends across the lower end of bodysection 17, and is formed of a frangible material, such as a frangiblealuminum or resinous plastic material adapted to be broken or rupturedby the force of the generated gases when charge 22 is fired to thusallow the cement to pass downwardly through the body and out its loweropen end behind the plug 24. As will be brought out in greater detail ata later point, the frangible wall 28 may be attached to, and formessentially a portion of, the plug unit 24, so that it acts to suspendthe plug in its initial Fig. 1 position within the tool. Wall 28 mayhave a relatively thick circular portion 29 toward its center, andcarrying a reduced thickness annular peripheral por tion 30 about theedge of the disc. This peripheral portion 30 may rest downwardly againstand annularly engage an annular shoulder 31 formed in the upper endof-body section 16, and may be held downwardly against that shoulder 31by threadedly connecting body section 17 into threaded bore 32 formedin'the upper portion of section 16 above shoulder 31. The threaded bore 32of course has an internal diameter which is greater than the internaldiameter of shoulder 31, to allow disc 28 to be inserted downwardlythrough bore 32 into engagement with shoulder 31. The disc 28 is strongenough at all points to support the weight of the cement, and inaddition to withstand a gas pressure above the cement of a prdeterminedvalue (preferably between about 80 and 200 psi.) and for best resultsabout 150 psi. The pressure referred to is of course a differentialpressure, as between the pressure of the gases within the tool above thecement, and the fluid pressure at the outside of the body, andparticularly the pressure beneath wall 28. When this dilferentialpressure reaches the predetermined value, the peripheral portion 30 ofdisc 28 breaks along an annular line defined by the inner edge ofshoulder 31, so that the plug, cement, and most of the wall 28 can berapidly ejected downwardly from the tool body.

Portion 18 of the tool body carries a number of outwardly seating checkvalves 33 serving to prevent outwardescape of the cement displacinggases. through the wall of the body, while permitting an inward flow of;

well fluid into the body when the pressure is reduced below that at itsoutside. These check valves may be of conventional ball check valveconstruction including spherical valve elements free for limitedmovement within cages 34- toward and away from seats 35.

The upper tubular portion 19 of the body is perforated at 36 to permitoutward flow of the generated gases against packer sleeve 23. Thispacker sleeve is formed of rubber or other resilient elastornericmaterial, and is peripherally clamped by bands 37 at its opposite endsto the end portions of perforated body section 19. As will be apparent,clamping rings 37 hold sleeve 23 in fluid tight sealing engagement withbody section 19 at two vertically spaced locations, between which thesleeve 23 is readily expansible tothe condition of Fig. 2 by thegenerated gases and is then resiliently returnable to the condition ofFig. 1 when the pressure within the tool returns to normal. The wireline 11 which suspends the tool 10 in the well is connected to a bail38, whose ends attach at 39 to upper body section 19.

The gas gun or filing chamber 21 comprises a cylindrical preferablymetallic vertically extending body containing the propellant charge 22,and closed at its upper end so that the gases produced by the propellantcharge are directed downwardly from the lower open end of gun 21 andagainst the upper surface of the cement 20. Firing current is deliveredto the propellant or explosive charge 22 from a battery 40 at thesurface of the earth, and under the control of a switch 41 also at thesurface of the earth. One side of the power source is connected to thecharge by being grounded (say at 42) to the body of the tool, withcurrent being carried from the conductive body of the tool to the chargethrough one or more contacts 43 attached to the lower end of charge 22and engaging the electrically conductive wall of gun barrel 21. Thesecontacts 43 may also serve to releasably retain the charge in itsillustrated Fig. 1 position within the gun, as is brought out in greaterdetail in my Patent 2,696,259. The second side of the power source isconnected to the charge through a wire 44 extending downwardly withinthe well and connecting to a terminal 45 which is electrio-allyconnected to a contact 46 for engaging an upper electrically conductivecontact on charge 22. As will be apparent, terminal 45 and contact 46are of course electrically insulated from the body of the tool. Thus,when switch 41 is closed at the surface of the earth, firing current ispassed through charge 22 causing it to burn and produce large quantitiesof gases in the tool.

Gas gun 21 is preferably mounted for limited upward recoiling movementupon firing, and for this purpose may have a portion 47 near its upperend which is verticaily slidable within shoulder portion 48 in a bushing49, the bushing being threadedly connected into upper body section 19. Anut 50 on the upper end of the gas gun is engageable with shoulder 48 ofthe bushing to limit downward movement of the gun, while integral flange51 on the gun barrel limits its upward recoiling movement at the Fig. 2position.

Propellant charge 22 preferably comprises an explosive or combustiblecharge characterized by a capacity to pro duce a relatively prolongedpressure and temperature surge rather than a sharp instantaneousexplosion to thus eiiectively force the cement from the container andinto the well zone without danger of rupturing the tool body itself, orpacker 23, or any of the other portions of the device with the exceptionof the purposely frangible element 28. For best results, the propellantcharge should be selected to burn over an extended period of betweenabout one and one-half and thirty seconds under the particularhydrostatic pressure encountered at the zone being cemented. Thepressure differential developed by the gases, between the inside andoutside of the tool, should of course be sufliciently above the breakingpressure of disc 28 to assure rupturing of that disc by the gaspressure, and yet should not be an excessive value which might damagethe plug or other parts. Preferably, the maximum pressure differentialdeveloped by the gases is be tween about 160 and 500 p.s.i., and sayabout 300 p.s.i. for best operation where the disc 28 is constructed tobreak at 150 p.s.i.

Referring now particularly to Figs. 3 through 6, plug 24 includes avertically extending shaft-like carrier member 52, which carries at itsvertically central portion an upwardly facing and upwardly flaring sealcup structure 53 for engaging and forming a seal with casing 13, tosupport the cement in the casing. This seal cup structure 53 isinitially held in the radially constricted condition of Fig. 3, byreception within the cylindrical lower body section 16, and is adaptedto resiliently expand to the Fig. 2 active position when the plug isejected from the lower end of section 16. Structure 53 may include anannular rigid ring 54 carried about and attached in fixed relation toshaft 52, as by annular welding at 55. To the outer cylindrical surface56 of ring 54, there may be attached a reduced diameter tubular portion57 of a flexible annular seal cup element 58. This element 58 may beformed of a suitable rubber or other elastomeric material, preferablyextremely thin (say between about .010 and .020 inch), to be collapsibleinto an extremely small diameter tool body. The element 58 in its normalcondition flares upwardly as seen in Fig. 2, and in the broken lines inFig. 3, and is of course imperforate and fluid tight to form aneffective fluid seal in the well. The lower portion 57 of element 58 maybe sealed to ring 54 in any practical manner, as by annularly bonding orvulcanizing this portion to the ring.

In order to allow the use of such a thin seal cup element 58, thestructure 53 includes also a number of metal elements 59, which may beidentical one with the other, and have their lower ends 60 attached toring 54. These elements 59 are desirably formed of thin spring steel,typically about .002 of an inch thick, and are distributed uniformlyabout ring 54. As an example of one way in which portions 60 of elements59 may be secured to the ring, these portions may typically be clampedinwardly against portion 56 of element 58 by a clamping ring representedat 61.

As elements 59 extend upwardly above ring 54, they progressively flare,to normally form together a conical structure of a configurationcorresponding essentially to the normal Fig. 2 configuration of rubbercup 58. These parts 59 overlap circularly about the axis of shaft 52,and are capable of moving to positions of progressively increasingoverlap to allow the elements 59 to be collapsed or contracted With cup58 to the Fig. 3 full line position. The resiliency of elements 59however, normally urges those elements to their expanded Fig. 2positions and preferably tends to urge them slightly radially outwardlybeyond the Fig. 2 positions to assure effective engagement with thecasing 13 in the expanded condition of the apparatus. Also, it will ofcourse be apparent that each of the various elements or petals 59 has anormal curvature corresponding to the curvature of the cone defined bythese parts in the Fig. 2 positions of elements 5%. Each of the elements59 may be reinforced or strengthened along one of its edges by anessentially rigid typically metal rib 62 Welded or otherwise secured tothat edge, but terminated at the upper edge of ring 54 rather than beingin any way attached to that ring. Each of the various ribs 62 may lie ina plane which also contains the axis 63 of shaft 52, and moves radiallyin that plane upon expansion and contraction of the cup structure 53. Inall conditions of cup structure 53, the elements 59 desirably back up orsupport rubber cup 58 continuously across its entire area, except at theperipheral annular edge 64 of the cup which may project beyond elements59 to assure proper fluid tight sealing engagement with casing 13.

At its upper end, shaft 52 carries a number of evenly circularly spacedfingers 65 which are adapted to engage casing 13 in a manner lockingplug 24 against down-- ward movement in the well after ejection of theplug downwardly from the tool body. Similarly, the lower end of the plugcarries a second series of fingers 66 which will function to lock theplug against upward movement relative to the casing. The fingers 65 arepivotally mounted for swinging movement relative to shaft 52 between thefull line retracted positions of Fig. 3, and the expanded positions ofFig. 2 (broken lines in Fig. 3). For thus mounting the fingers, shaft 52carries two axially abutting rings 67 and 68, between which there isclamped in fixed position a ring 69 of cylindrical cross section. Thefingers 65 have openings through which ring 69 passes, so that thefingers are free to swing radially outwardly between their differentpositions and about ring 69. As will be apparent the ring 69 is ofcourse centered about axis 63. The different fingers 65 have their innerends received Within recesses or grooves 70 (see Fig. 4) in rings 67 and68, to allow engagement of fingers 65 with rings 69. Between thelocations of recesses 70, rings 67 and 68 have abutting faces containingopposed complementary grooves 71 shaped to exactly receive and confinethe ring 69 between rings 67 and 68. Ring 69 may be interrupted at onepoint along its circular extent, say at the point 72 in Fig. 4, so thatby slightly expanding ring 69 at this point and before assembly of theunit, the various fingers 65 may be slipped onto ring 69. Ring 69 isthen returned to its normal condition, and is positioned between rings67 and 68, with fingers 65 received within grooves 70. All of thevarious parts are then attached to the upper end of shaft 52 while inthis condition. To effect this attachment, the inner bore 73 of ring 67may be threaded, to be threadedly connectible onto the upper end 74 ofshaft 52, to thus tighten ring 68 downwardly against a shoulder 75 onshaft 52. The ring 68 may have a cylindrical rather than a threadedinternal bore.

The fingers 65 are yieldingly urged radially outwardly toward a positionbeyond that of Fig. 2, by a coil spring 76 which is disposed about shaft52 between ring 54 and an upper annular element 77 which is slidableaxially along shaft 52. Element 72 has a flange 78 engaging the innersurfaces 79 of fingers 65, and acting to cam fingers 65 radiallyoutwardly when element 77 is moved upwardly. Spring 76 is at all timesunder compression, to continuously urge element 77 upwardly and thusurge fingers 65 radially outwardly.

At their outer ends, fingers 65 taper to points 80, which project intothe wall of casing 13 in the outwardly expanded Fig. 2 position of thefingers, to thus very effectively grip the casing and. prevent downwardmovement of the plug and fingers relative to the casing. In this Fig. 2position of the fingers, these fingers preferably flare downwardly, sothat any downward force exerted against the plug can only tend totighten the engagement between the fingers and the casing. Extendinginwardly from point 80 each of the fingers has a typically curving camsurface 81, which acts to engage the wall of body section 16 in the Fig.3 full line positions of the fingers, and to hold the points 80 of thefingers out of holding engagement with the tubular body member 16. Thus,the fingers 65 do not prevent the plug from moving downwardly within andfrom body section 16, and yet do effectively prevent downward movementof the plug relative to casing 13, and beyond the Fig. 2 position ofengagement with the casing. Surfaces 81 are so designed as to allow thepoints 80 to move into holding engagement with a surrounding tubularmember only after the fingers have swung outwardly beyond apredetermined position, typically a position of about 30 angularity withrespect to a radius of axis 63, which position should be between thefull line and broken line positions of Fig. 3.

The lower set of fingers 66 is identical with the upper set of fingers65, except that the lower fingers 66 are inverted to prevent upwardrather than downward movement of the plug within the casing (withoutinterfering with movement of the plug while it is within tubular bodysection 16). Without discussing the means of retaining fingers 66 indetail, it will sufiice merely to state that these fingers are retainedon the threaded lower end 82 of shaft 52 by three rings 83, $4 and 85corresponding to rings 67, 68 and 69 respectively. Also, fingers 66 areyieldingly urged to their expanded positions by an element 86 and aspring 87 corresponding to parts 77 and 76 respectively associated withthe upper fingers. When plug 24 is not contained within any tubularelement, the parts 76, 77, 86 and 87 will function to yieldingly urgethe fingers to positions outwardly beyond the Fig. 2 positions, to thusassure effective spring urged holding engagement of the fingers withcasing 13 in the Fig. 2 condition.

In preparing the tool for use, the first step may be to remove lowerbody section 16 from the rest of the body, and to then slip plug 24axially upwardly into the lower end of body section 16, with lower nosemember 25 removed from section 16. During such insertion, the disc 28and its retaining nut 88 are not attached to plug 24, and the fingers 65and 66, as well as parts 58 and 59 of cup structure 53, are all manuallyheld in their inwardly retracted or collapsed positions of Fig. 3 asthey are slipped into body section 16. When the plug has reached theFig. 3 position in section 16, disc 28 is inserted downwardly intosection 16 to engage shoulder 31, and nut 88 is then tighteneddownwardly on shaft 52 and against disc 28 to clamp shoulder 31 betweenelements 28 and 67, and thus secure plug 24 in fixed position withinsection 16. Nose member 25 is then attached to section 16, and section16 is threaded onto the lower end of section 17. Gas gun 21 is thenremoved from the upper end of the tool as permitted by the threadedmounting of bushing 49, and cement is filled into the tool body throughits open upper end to a proper predetermined level. Sufiicient cementwill normally be poured into the body to substantially fill its tubularportion 17. A gas producing propellant or explosive charge 22 is slippedinto the firing gun 21 through its open lower end, and the gun andcontained charge are then connected into the tool body as seen in Fig.l.

The tool is lowered into the well to the zone to be cemented, and theelectrical switch 41 is then closed at ground level to admit currentfrom battery 40 to a fuse contained within charge 22. The resultingignition of charge 22 produces a large quantity of high temperaturegases under pressure, which gases are directed downwardly by gun 21against the body of cement 20. The increase of pressure within the toolforces packer sleeve 23 outwardly to its Fig. 2 position to seal off thecasing against upward fluid flow, and this pressure simultaneouslyexerts a downward force against cement 24 Until the pressure within thetool body and above cement 21) reaches the predetermined ejectionpressure for which disc 28 is designed, the disc 28 supports the cementand prevents its downward movement within the tool body. However, whenthat critical pressure is reached, typically 150 psi. (after expansionof packer 23 to its sealing position), the peripheral relatively thinportion 3i! of disc 28 suddenly ruptures along an annular line justinwardly of shoulder 31, so that the gas pressure may then very suddenlyeject the cement and plug 24 downwardly and from the tool body. Becausethe pressure has built up before rupture of disc 28, the plug movementdownwardly to the Fig. 2 position is very rapid, and assures movement ofthe plug to a position spaced somewhat below body section 16 beforefingers 65 can stop its downward movement. The cement flows downwardlyfrom the tool body behind the plug, to form the desired cement closureacross the well above cup structure 53. Preferably, the bodysection 16contains side openings at 190 near its upper end, but beneath shoulder31, through which openings some of the cement and the gas force can bebled laterally as soon as disc 28 has ruptured, to thus prevent thedevelopment of an excessive force against the plug which might otherwisedamage cup structure 53 or other portions of the plug. The initial forceof the gases causes upward recoiling movement of the gas gun, whichmovement is abruptly stopped at the Fig. 2 position of the gun in amanner setting up a shock wave in the gases which may assist inrupturing disc 28 assuming that approximately the critical predeterminedpressure has been reached.

Nose member 25, after being disconnected from the body of the tool bydownward movement of the plug, may fall downwardly to the bottom of thewell. The high temperature of the gases which are generated above cement20 causes the cement to set much more rapidly than would be possible inthe absence of such heat. Also, the pressure exerted against the cementby the gases assists in squeezing out all of the excess moisture fromthe cement, to thus further assure its rapid setting. As the pressurewithin the tool diminishes after an operation, packer sleeve 23resiliently returns to its normal position of Fig. l, permitting removalof the tool from the well, and check valves 33 permit inward passage ofwell fluid into the tool to equalize the pressures at the opposite sidesof the tool body. When the tool is withdrawn upwardly from the Well,plug 24 and the cement remain in the well, and may be subsequently veryeasily drilled out to again provide access to the lower portion of thewell. It will of course be apparent that all of the various body partsand other parts of the apparatus, with the exception of the purposelyshearable element 23, must be strong enough to withstand the force ofthe gases generated by the charge 22 upon firing. It is noted that, inthe completed well closure formed by plug 24 and the cement, the fingers65 and other portions of the plug which are positioned above cupstructure 53 act as metal reinforcing elements within the cement, tothus maximize the strength of the reinforced cement combination. It isalso pointed out that in some instances, the plug and cement can beeffectively set without the necessity for the upper packer element 23,in which case upper body section 19 would of course be imperforaterather than contain the apertures 36. This variational form of theinvention is shown fragmentarily in Fig. 11, in which the body section19a corresponds to body section 19 of Fig. l, but is imperforate.Otherwise, the Fig. 11 arrangement would be identical with that of Figs.1 to 7.

Figs. 8 and 9 represent fragmentarily a variational form of theinvention, which may be considered as essentially identical with that ofFigs. 1 to 7 except for the substitution of a different type of plug 24bfor the plug 24 of the first form of the invention. This plug 24b iscontained within a lower section of the body corresponding to section 16of Fig. 1, section 9t being vertically elongated to accommodate therather elongated plug 24b. Plug 24b includes a vertically extending body91 about which is carried an outer tubular body 92 carrying a number ofresiliently deformable sealing cups or discs 93 typically formed ofrubber. These sealing cups 93 may be initially held in constrictedcondition within body section 90, and are adapted to resiliently expandoutwardly into engagement with liner 1312 when the plug is ejecteddownwardly from the lower end of the tool body. The carrier element 91of plug 24b has an upper series of circularly spaced downwardly flaringfingers 94 which are pivotally connected to carrier 91 as at 95, andwhich are initially held in their retracted positions of Fig. 8 byreception of the plug within body section 90.

A second but upwardly flaring series of gripping fingers 96 pivoted at97 to carrier 91 are provided at the lower end of carrier 91. A pair ofcollapsible springs 98 and 99 urge rings 100 and 161 axially againstfingers 94 and 96, to yieldingly urge those fingers radially outwardly,so that when plug 24b is ejected downwardly from the tool body by thegas force, fingers 94 and 96 expand into gripping engagement with. liner13b, and thenact to positively hold plug 24b in a fixed positionsomewhat beneath the lower end of the tool body. Thus, when the tool isfired, plug 24b serves essentially the same function as plug 24 of thefirst form of the invention, that is, plug 24b closes off the well boreat a location spaced beneath the tool body, and thereby requires thatthe displaced cement accumulate above the plug and form a closure acrossthe well bore. As in the first form of the invention, the cement 20b iscontained within the tool body above a frangible disc 28b, which isadapted to be ruptured by the force of the generated gases when thepropellant charge is fired, to thus allow the cement to be forceddownwardly through the tool body and out its lower end, with the plug241) of course being pushed downwardly in advance of and by the cement.Frangible horizontal wall 2812 may be retained in its illustrated Fig. 8position by reception of the circular peripheral edge of element 28bbetween a downwardly facing shoulder formed in the upper end of bodysection 90 and a clamping ring 104 which is threadedly connected intobody section 90 and against disc 28b. The disc 28]; may typically beformed of a suitable frangible resinous plastic material, a thin sheetof aluminum, or other suitable material.

If desired, plug 24b may have a shaft 102 extending downwardly throughtubular carrier 91 and having an annular recess at 103 within whichinner projections on fingers 96 are movab-ly receivable so that downwardmovement of shaft 102 relative to the rest of the plug will swingfingers 96 laterally inwardly to retracted positions in which the plugmay be withdrawn upwardly from the well. Such downward movement of shaft102 may be efiected by a suitable fishing tool, which can simultaneouslyexert an upward pulling force on the upper portion 104 of the plug.Obviously such removal of the plug from the Well by a fishing tool wouldbe effected only under very unusual circumstances, in which for somereason the cement after displacement would not cover the upper end ofthe tool (as where the cement might virtually all be lost in theformation), and to remove the plug without further attempt at cementing.As in the first form of the invention, the fingers 94 and 96 are sodesigned that they will not grip tube 90 in holding relation, but willpositively gn'p casing 13b in a holding engagement preventing verticalmovement of the plug within the casing, after the fingers have beenallowed to expand outwardly into engagement with the casing.

Fig. shows still another form of the invention, in which all parts ofthe tool may be essentially identical with the device of Fig. 1 exceptthat a different form of plug 240 is substituted for the plug 24. Thisplug 240 includes a vertically extending shaft-like carrier member 106,on which are removably carried a pair of oppositely directed annularsealing cups 107 and 108 formed of resiliently flexible elastomericmaterial such as rubber. These cups 107 and 108 are initially retainedin a radially retracted condition within portion 109 of the tool body,and normally tend to laterally expand to a diameter to which theperipheral sealing edges or lips of cups 107 and 108 will annularlyengage the inner wall of liner 130 in fiuid tight sealing relation. Thetwo sealing cups 107 and 108 are carried by individual rigid preferablymetal rings 110 and 111, having an annular groove 112 within which theinner edges of cups 107 and 108 are received, with the material of thecups being vulcanized or otherwise tightly bonded to rings 110 and 111Within these grooves.

The upper ring 110 is initially held upwardly by an upper series ofgripping fingers 113 and bears upwardly against a nut 114 which isthreadedly connected onto carrier 106. The lower ring 111 is initiallyheld downwardly by a lower series of fingers 115 and bears against abottom nut 116. Rings 110 and 111 are sufiiciently loose fits on carrier106 to be displaced relatively together axially along carrier 106 by theforce generated by the propellant charge, such displacement of rings and111 being limited by engagement of these rings with the upper and lowersides of an annular enlargement 117 on carrier 106. In the positions inwhich rings 110 and 111 are in substantial contact with enlargement 117,the rings are retained against returning movement away from enlargement117 by means of spring detent elements 118 contained in radial bores inrings 110 and 111 and receivable within annular grooves or recesses 119in carrier 106.

In the initial inactive condition of plug 240, fingers 113 and are heldstationarily relative to carrier 106 in the full line positions of Fig.10. In these positions,

the fingers 113 of the upper set of fingers are arranged as a series ofcircularly spaced elongated elements which fiare upwardly from theirlower ends 120 (attached to carrier 106), to their upper ends 121 (whichbear against ring 110). The lower ends 120 of fingers 113 are mountedwithin individual circularly spaced bores 122 formed in the peripheralportion of an upper part 123 of carrier enlargement 117. The radiallyouter surface 124 of portion 123 of the carrier may flare upwardly atapproximately the same angle as fingers 113.

The finger mounting bores 122 in the carrier enlargement are positionedso that the bore walls intersect or are interrupted by the outer surface124 of that part of the carrier, so that each of the finger mountingbores 122 is opened along its outer side, but for a width narrower thanthe diameter of the bore and contained finger (the fingers preferablybeing of circular transverse section). Thus, the material of carrier 106acts to only partially embrace the outer side of each of the fingers113, to initially hold the fingers in fixed relation to carrier 106,through the material which retains fingers 113 at their outer sides issufficiently thin to be sheared or deformed by the fingers upon firingof the propellant charge, to thereby allow the fingers to swingoutwardly to the broken line positions of Fig. 10. The lower ends offingers 113 bear against an annular flange 125 formed on carrierenlargement 117, so that those lower ends of the fingers are containedin a manner guiding fingers 113 for the desired outward swingingmovement. The lower set of fingers 115 are identical with upper fingers113, except that fingers 115 fiare downwardly, and swing outwardly in adirection the reverse of fingers 113. The upper ends 126 of fingers 115are confined within individual bores 127 formed in the periphery of alower portion 128 of enlargement 117, which portion of the enlargementhas a downwardly flaring radially outer surface 129 of a diameter suchthat the outer sides of bores 127 are interrupted in the same manner asbores 122, to allow outward swinging movement of fingers 115 when thepropellant charge is fired.

The outward swinging movement of fingers 113 and 115 is effected by acamming engagement of rings 110 and 111 with the fingers. Moreparticularly, the ends 121 and 130 of fingers 113 and 115 are receivedwithin individual notches or guide recesses 131 in rings 110 and 111,which notches have inner walls 132 extending at an angle relative to theaxis of carrier 106, such that movement of rings 110 and 111 relativelytogether-along carrier 106 acts to cam the engaged ends of the fingers113 and 115 radially outwardly. When this camming action proceeds to anextent such that the ends of the fingers 113 and 115 move out of notches131, the inner sides of fingers 113 and 115 then move into engagementwith points 133 on rings 110 and 111, and this engagement serves tofurther cam the fingers radially outwardly until their pointed ends 121and 130 bite into the inner surface of liner 1312, so that the upperfingers 113 very positively retain plug 240 against upward displacement,while lower fingers 115 positively retain the plug against downwarddisplacement. As previously brought out, rings 110 and 111 are retainedin this locked position by detents 118, so that the plug is thenpositively locked in a fixed position within the liner. In thiscondition, fingers 113 and 115 preferably act as backing elements forbacking up cups 107 and 108 to prevent undue flexure' of these cups.

As in the previous forms of the invention, the cement in Fig. may beinitially supported by a frangible disc 280, which may be identical withthe disc 21% of Figs. 8 and 9. Also, the lower end of section 109 inFig. 10 may removably carry a bottom nose member 250 which isfrictionally or otherwise attached to the bottom of section 109 in amanner such that the nose member can be easily blown downwardly by theexplosive force.

When the tool of Fig. 10 is tired, the operation is the same as in theprevious forms of the invention except as to the manner in which theplug 240 is locked in position in the well. As this plug 24c is ejecteddownwardly, the lower downwardly facing seal cup 108 of this plugengages the liquid contained in the well, and the resist ance ottered bythis liquid causes pressurized cement to actuate the seal cups 107 and108 relatively together, to progressively cam fingers 113 and 115radially outwardly into gripping engagement with liner 13c. Cups 1&7 and16$ of course resiliently expand into sealing engagement with the lineror casing 130, to close ofl the well bore and support the cement in thewell. By the time the gripping fingers 113 and 115 of plug 24c have beenactuated to their holding positions of engagement with casing 130, theplug has moved downwardly to a position somewhat below the lower end ofthe tubular body of the tool, to thus allow an annular space between thebody and the upper seal cup through which cement may flow from the tool.The plug of Fig. 10 is, in any suitable manner, so designed as to assureagainst gripping engagement of fingers 113 and 115 with the interior ofthe tool section 109. For this purpose, the outer pointed ends 130 offingers 113 and 115 may have surfaces 135 adjacent their points whichengage section 109 and hold the points out of gripping engagement withthat section, but with these surfaces 135 being so formed as to allowgripping engagement of the points with the greater diameter casing 13cafter further radial expansion of the fingers. Also, the fingers 113 and115 and the rings 110 and 111, are all so formed as to allow enoughclearance between the fingers and the cups 107 and 108 to prevent thefingers from biting into the cups as the fingers swing outwardly.

I claim:

1. Apparatus for forming a closure in a well bore, comprising a hollowvertically extending body adapted to be lowered to a zone within thewell, a mass of cementitious material in the body adapted to be ejectedfrom the lower end of the body by gas pressure acting downwardly againstthe material, a plug carried by the body in an inactive position beneathsaid cementitious material and adapted to be ejected downwardly from thebody with said cementitious material and to an active bore pluggingposition, said plug including holding means engageable with the sidewall of the well after said downward ejection and operable to hold theplug against further downward movement in the well, said plug includingclosure means engageable with the bore wall after said downward ejectionand operable to close the bore against downward flow of the cementitiousmaterial past the plug, a gas producing propellent charge carried by thebody and adapted and positioned to produce a large quantity of hightemperature and high pressure gases above said cementitious material atsuch a location and in such quantity as to rapidly force thecementitious material and plug downwardly relative to and from the bodyby the fluid pressure of said gases to thereby close the bore, saidcementitious material being positioned to be highly pressurized by thegas force after the plug has been ejected so that said material, beingretained by the plug against further downward movement, is forced israpidly set by the high pressure and high temperature of the gases, apacker carried by the body and adapted outwardly against the well borewall by the gases, and to close the bore at a location spaced above saidactive position of the plug to thereby confine the pressurizedcementitious material and gases vertically between the plug and packer,said body being constructed to be free for withdrawal upwardly from thewell without the plug and cement after firing of the propellent charge,and a seal structure supported in the body vertically between thecementitious material and said plug and preventing fiow of said materialdownwardly into contact with the plug and constructed to shear under theforce of said gases to allow downward movement of the material rela--tive to the body.

2. Apparatus for forming a closure in a well bore, comprising a hollowvertically extending body adapted to be lowered to a zone within thewell, a mass of cementitious material in the body adapted to be ejectedfrom the lower end of the body by gas pressure acting downwardly againstthe material, a plug carried by the body in an inactive position beneathsaid cementitious material and adapted to be ejected downwardly from thebody with said cementitious material and to an active bore pluggingposition, said plug including holding means engageable with the sidewall of the well after said downward ejection and operable to hold theplug against further downward movement in the well, said plug includingclosure means engageable with the bore wall after said downward ejectionand operable to close the bore against downward flow of the cementitiousmaterial past the plug, a gas producing propellent charge carried by thebody and adapted and positioned to produce a large quantity of hightemperature and high pressure gases above said cementitious material atsuch a location and in such quantity as to rapidly force thecementitious material and plug downwardly relative to and from the bodyby the fluid pressure of said gases to thereby close the bore, saidcementitious material being positioned to be highly pressurized by thegas force after the plug has been ejected so that said material, beingretained by the plug against further downward movement, is forcedoutwardly against the well bo're wall by the gases, and is rapidly setby the high pressure and high temperature of the gases, a packer carriedby the body and adapted to close the bore at a location spaced abovesaid active position of the plug to thereby confine the pressurizedcementitious material and gases vertically between the plug and packer;said body being constructed to be free for withdrawal upwardly from thewell without the plug and cement after firing of the propellent charge,a seal structure supported in the body vertically between thecementitious material and said plug and preventing flow of said materialdownwardly into contact with the plug and constructed to shear under theforce of said gases to allow downward movement of the material relativeto the body, and means attaching said shearable seal structure to theupper end of said plug.

3. Apparatus as recited in claim 2, in which said body has a lowertubular portion beneath said seal structure and containing said plug andhaving. an apertured side wall through which the cementitious materialcan bleed laterally from the body during downward movement of the plugto prevent the exertion of excessive force against the plug.

4. Apparatus for forming a closure in a well here, comprising a hollowvertically extending body adapted to be lowered to a zone within thewell, a mass of cementitious material in the body adapted to be ejectedfrom the lower end of the body by gas pressure acting downwardly againstthe material, a plug carried by the body in an inactive position beneathsaid cementitious material and adapted to be ejected downwardly from thebody with said cementitious material and to an active bore pluggingposition, said plug including holding means engageable with the sidewallof the well after said downward ejection and operable to hold the plugagainst further downward movement in the well, said plug includingclosure means engageable with the bore wall after said downward ejectionand operable to close the bore against downward flow of the cementitiousmaterial past the plug, a gas producing propellent charge carried by thebody and adapted and positioned to produce a large quantity of hightemperature and high pressure gases above said cementitious material atsuch a location and in such quantity as to rapidly force thecementitious material and plug downwardly relative to and from the bodyby the fluid pressure of said gases to thereby close the bore, saidcementitious material being positioned to be highly pressurized by thegas force after the plug has been ejected so that said material, beingretained by the plug against further downward movement, is forcedoutwardly against the well bore wall by the gases, and is rapidly set bythe high pressure and high temperature of the gases, and a packercarried by the body and adapted to close the bore at a location spacedabove said active position of the plug to References Cited in the fileof this patent UNITED STATES PATENTS 2,605,846 Van Brunt et al. Aug. 5,1952 2,618,345 Tucker Nov. 18, 1952 2,646,845 Schillinger July 28, 19532,675,878 MacGregor Apr. 20, 1954 2,696,259 Greene Dec. 7, 1954

